Takashi Abe

Since stickiness of skin can cause skin diseases, it is necessary to deal with this problem by using basic cosmetics. However, excessive use of basic cosmetics can worsen adverse skin conditions. In addition, the optimal state of the skin after the use of basic cosmetics has not yet been quantified. In this study, we measured and examined the response to adhesive force using an ultra-compact tactile sensor, and then compared the response to adhesive force of basic cosmetics. As a result, we obtained a response proportional to the strength of the adhesive force. In addition, responses differed greatly depending on the type of basic cosmetics and whether or not there was any residual liquid.

Thickness shear mode (TSM) resonators consisting of metal films and quartz plates are widely used for sensor applications such as film thickness monitoring, force sensors, and odor sensors. However, the current sensor geometry prevents further improvements in its sensitivity and stability. Thinning the plate is necessary for high sensitivity, and advanced fabrication technologies are required for their commercialization. The solution is to use a support substrate to increase the mechanical strength, which can guide the transmittance of the electric field. Herein, we report a TSM resonator bonded to a support substrate. An AT-cut quartz resonator with a floating electrode on the top side was bonded to the support substrate. Two excitation electrodes were placed under the substrate. The support substrates evaluated in this study included borosilicate glass, Z-cut quartz crystals, and AT-cut quartz crystal plates. The quartz crystal resonator (QCR) bonded to the AT-cut quartz crystal plate and positioned at 90° to the crystallographic x-axis shows an excellent temperature coefficient of frequency of −60 ± 14 ppb/°C for a temperature range 11–40 °C. The proposed method reduces temperature sensitivity to 1/4 or less compared to that without a substrate. Furthermore, the resonator could be used as a quartz crystal microbalance. The proposed method may inspire further high-frequency QCR-based biochemical chips or various sensor applications with TSM resonators.

This paper addresses physical and chemical resistance evaluation of tactile sensors. We have developed cantilever-type MEMS tactile sensors embedded in the elastomer. In this work, we used a combination of silicone elastomer with excellent mechanical properties and fluoroelastomer with excellent chemical resistance. As a new embedding method for the sensor, we devised a method of embedding with PDMS with low creep and coating with a fluoroelastomer for surface protection. We further performed three evaluations to demonstrate the physical and chemical resistance of sensors. Consequently, using the devised method, we have demonstrated that the sensor with both physical and chemical resistance are feasible.

In this paper, we report the development of time‐delay analysis method of inductance and capacitance for microfluidic circuit. The sensor used in this method is composed of the sensing inductor (SI) and the sensing capacitor (SC) with a microfluidic circuit. This sensor measures inductance and capacitance in a time difference by delaying with microfluidic circuit. We confirmed that SI and SC have different responses to conductive and dielectric solution. This research is expected to be applied to the combined analysis of liquid samples.

The coronavirus disease 2019 (COVID-19) has caused a serious disease burden and poses a tremendous public health challenge worldwide. Here, we report a comprehensive epidemiological and genomic analysis of SARS-CoV-2 from 63 patients in Niigata City, a medium-sized Japanese city, during the early phase of the pandemic, between February and May 2020. Among the 63 patients, 32 (51%) were female, with a mean (±standard deviation) age of 47.9 ± 22.3 years. Fever (65%, 41/63), malaise (51%, 32/63), and cough (35%, 22/63) were the most common clinical symptoms. The median C_t value after the onset of symptoms lowered within 9 days at 20.9 cycles (interquartile range, 17–26 cycles), but after 10 days, the median C_t value exceeded 30 cycles (p < 0.001). Of the 63 cases, 27 were distributed in the first epidemic wave and 33 in the second, and between the two waves, three cases from abroad were identified. The first wave was epidemiologically characterized by a single cluster related to indoor sports activity spread in closed settings, which included mixing indoors with families, relatives, and colleagues. The second wave showed more epidemiologically diversified events, with most index cases not related to each other. Almost all secondary cases were infected by droplets or aerosols from closed indoor settings, but at least two cases in the first wave were suspected to be contact infections. Results of the genomic analysis identified two possible clusters in Niigata City, the first of which was attributed to clade S (19B by Nexstrain clade) with a monophyletic group derived from the Wuhan prototype strain but that of the second wave was polyphyletic suggesting multiple introductions, and the clade was changed to GR (20B), which mainly spread in Europe in early 2020. These findings depict characteristics of SARS-CoV-2 transmission in the early stages in local community settings during February to May 2020 in Japan, and this integrated approach of epidemiological and genomic analysis may provide valuable information for public health policy decision-making for successful containment of chains of infection.

In this paper, we report a development of quartz crystal complex capacitive sensor with microelectrode array for local detection of liquid sample. This sensor is composed of the sensing capacitor (SC) with microelectrode array and quartz crystal resonator (QCR). It is a contactless capacitive sensor using out‐of‐plane electric field of a planer SC. We succeeded in confining the electric field by placing microelectrode array on the SC and improving the spatial resolution of the sensor. This sensor enables local capacitive detection of target materials. This sensor is expected to be applied to the detection system of μ‐TAS.

In this study, we developed a dry‐nano‐polishing technique using reactive ion etching for ultra thin titanium wafer. The surface of titanium coated with photoresist is polished by reactive ion etching using SF6 /C4F8 gas. Etching speed of titanium and photoresist were adjusted to close to each other by changing temperature and ratio of SF6 /C4F8 gas. By etching titanium under these conditions, the smooth surface shape of the resist was transferred to titanium. By combining with photolithography, it is possible to polish a specific part.

Humans recognize surface texture of objects by perception of force and vibration during contact. In our previous work, it is demonstrated that multi-axial contact force can be detected by tactile sensor using Si microcantilevers with thin film strain gauge embedded in the elastomer. In this work, to detect vibration, Si microcantilever with PZT thin film embedded in the elastomer has been newly fabricated and characterized. As a result, the output voltage depending on vibration frequency can be successfully obtained from PZT on the fabricated microcantilever. Furthermore, the microcantilever has been thinned by dry etching process after fabrication and it is suggested that sensitivity and frequency characteristics of the vibrational tactile sensor can be controlled.

In this work, we have attached the developed MEMS tactile sensor to the tongue model of elastic urethane resin for oral care simulation. This sensor can detect both normal and shear loads as resistance change of the strain gauge on the micro-cantilever fabricated on a Si substrate and embedded in the PDMS elastomer. Output of tactile sensor applying normal load to the tongue model was measured and it is confirmed that output depends on hardness of the tongue model and the point where normal load is applied. Therefore, it is considered that contact information to tongue model including force strength and position can be obtained from output of tactile sensor.